Transmission of nevirapine-resistant HIV type 1 via breast milk to infants after single-dose nevirapine in Beira, Mozambique.

Acquisition of nevirapine (NVP)-resistant human immunodeficiency virus type 1 (HIV-1) by breast-feeding infants after receipt of single-dose NVP to prevent mother-to-child transmission is not well defined. A prospective observational study of 307 infants evaluated the rate of breast milk transmission of NVP-resistant HIV and the concentrations of mutants over time. NVP resistance was detected in 9 of 24 infants (37.5%; 95% confidence interval, 18.8%-59.4%) infected via breast milk. Eight had a pure mutant HIV population at the time infection was first detected, and majority mutant populations persisted in all 6 infants with follow-up specimens. Infection of breast-feeding infants with NVP-resistant HIV resulted in mutants persisting as the dominant virus, which may indefinitely compromise treatment with NVP-based antiretroviral regimens.

Effects of short-course zidovudine on the selection of nevirapine-resistant HIV-1 in women taking single-dose nevirapine.

Single-dose nevirapine (sdNVP) given to prevent mother-to-child-transmission of HIV-1 selects NVP-resistance. Short-course zidovudine (ZDV) was hypothesized to lower rates of NVP-resistance. HIV-1 infected pregnant women administered sdNVP with or without short-course ZDV were assessed for HIV-1 mutations (K103N, Y181C, G190A, and V106M) prior to delivery and postpartum. Postpartum NVP-resistance was lower among 31 taking ZDV+sdNVP compared to 33 taking only sdNVP (35.5% vs. 72.7%; χ2 P = .003). NVP mutants decayed to <2% in 24/35 (68.6%) at a median 6 months postpartum, with no differences based on ZDV use (logrank P = .99). Short-course ZDV was associated with reduced NVP-resistance mutations among women taking sdNVP.

Nevirapine-Resistant HIV-1 DNA in Breast Milk After Single-Dose Nevirapine With or Without Zidovudine for Prevention of Mother-to-Child Transmission.

Among 30 human immunodeficiency virus type 1 (HIV-1)-infected women who received single-dose nevirapine (NVP), 17 (57%) had NVP-resistant HIV-1 detected in breast milk. NVP resistance in breast milk persisted for at least 8 months postpartum and was apparently transmitted to at least 1 infant. NVP resistance was detected less often in women who also received zidovudine.

Nevirapine resistance by timing of HIV type 1 infection in infants treated with single-dose nevirapine.

BACKGROUND: In women, single-dose nevirapine for prophylaxis against mother-to-child transmission of human immunodeficiency virus type 1 (HIV-1) selects for nevirapine-resistant HIV-1, which subsequently decays rapidly. We hypothesized that the selection, acquisition, and decay of nevirapine-resistant HIV-1 differs in infants, varying by the timing of HIV-1 infection. METHODS: We conducted a prospective, observational study of 740 Mozambican infants receiving single-dose nevirapine prophylaxis and determined the timing of infection and concentrations of nevirapine-resistant HIV-1 over time. RESULTS: Infants with established in utero infection had a high rate (87.0%) of selection of nevirapine-resistant HIV-1 mutants, which rapidly decayed to undetectable levels. The few without nevirapine resistance received zidovudine with single-dose nevirapine and/or their mothers took alternative antiretroviral drugs. Infants with acute in utero infection had a lower rate of nevirapine-resistant HIV-1 (33.3%; P = .006, compared with established in utero infection), but mutants persisted over time. Infants with peripartum infection also had a lower rate of nevirapine-resistant HIV-1 (38.1%; P = .001, compared with established in utero infection) but often acquired 100% mutant virus that persisted over time (P = .017, compared with established in utero infection). CONCLUSIONS: The detection and persistence of nevirapine-resistant HIV-1 in infants after single-dose nevirapine therapy vary by the timing of infection and the antiretroviral regimen. In infants with persistent high-level nevirapine-resistant HIV-1, nevirapine-based antiretroviral therapy is unlikely to ever be efficacious because of concentrations in long-lived viral reservoirs. However, the absence or decay of nevirapine-resistant HIV-1 in many infants suggests that nevirapine antiretroviral therapy may be effective if testing can identify these individuals.